I have recorded all the price spreads for the various grades of gas at the stations in Ottawa and I keep that list updated regularly as spreads change often.. Some Petro-Canada stations have a +9 cents for mid-grade, +16 cents for premium and +18/19 cents for Ultra94 on the Ontario side, versus 9/17 cents on the QC side. Some Esso's have very different price spreads where the mid and premium grades always end in .9 even though the regular might end with a .2, but the minimum spread is always at least +9 cents for mid-grade.